Conventionally, there have been light-emitting modules, as commercialized products, that convert a portion of blue light emitted from a blue LED into yellow light with use of a wavelength conversion material, and that mix an unconverted portion of the blue light and the yellow light resulting from the conversion to obtain white light.
However, white light obtained by such light-emitting modules as described above tends to have poor color rendering properties since the white light does not contain a sufficient amount of red component. Accordingly, Japanese Unexamined Patent Application Publication No. 2008-235458 proposes a technique for obtaining white light having excellent color rendering properties by supplementing the white light with a red light component by means of a red LED that emits red light, and mixing blue light, yellow light, and red light.
However, the structure disclosed in Japanese unexamined patent application publication No. 2008-235458 has the following problem. Suppose that a white light source and a red light source have different light distribution characteristics. In this case, a difference occurs in the relative illuminance of each color light source at the central portion and peripheral portion of the illumination target surface. Also, variations in light chromaticity occur between the central portion and peripheral portion of illumination light.
It is desirable that regardless of the difference in the light distribution characteristics of each color light source, the color unevenness of illumination light be suppressed by reducing the difference in the illuminance ratio of each color light source at the central portion and peripheral portion of the illumination target surface.
In view of the above problem, an aim of the present disclosure is to provide a light-emitting module that reduces the color unevenness of illumination light.